Process of making indoxyl, &amp;c.



UNITED STATES PATENT OFFICE.

BENNO HOMOLKA AND OTTO LIEBKNEOHT, OF FRANKFORT-ON-THE-MAIN, GERMANY, ASSIGNORS TO FARBWERKE, VORM. MEISTER, LUOIUS & BRUNING, OF HOCHST-ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY.

PROCESS OF MAKING iNDOXYL, 8&0.

SPECIFICATION forming part of Letters Patent No. 704,804, dated July 15, 1902.

Application filed September 4, 1901.

1'0 alt whom, it may concern:

Be it known that we, BENNO HOMOLKA,Ph. D., and OTTO LIEBKNECHT, Ph. D., citizens of the Empire of Germany, residing at Frank- 5 fort-on-the-Main, Germany, have invented certain new and useful Improvements in Processes of Making Indoxyl, 850., of which the following is a specification.

We have found that a good yield of indoxyl may be obtained by the action, of sodium amid on the so-called phenylglycinphenylglycin, (phenylglycinphenylglycidz) C0.0H..NH.G u CGHEN i omcdorr G (Journ. f. Prokt. Chem. (2) A32; Ber. XXII, 1803; Beilstein Ill, Edit. Vol. 2, p. 430.) The formation of indoxyl occurs already at the melting-point of the sodium amid-that is to 20 say, at about 125 centigrademore rapidly and completely, however, at a higher temperature, preferably at about 200 centigrade. The action of the sodium amid on the phenylglycinphenylglycin being lively, it is best to z 5 operate with suitable diluents. As such are specially appropriate the alkali hydroxids and the alkali cyanids or mixtures thereof.

The general mode of working consists by introducing the phenylglycinphenylglycin, 0 preferably in form of its salt, into the melt ing sodium amid with or without suitable diluents or by introducing the mixture of phenylglycinphenylglycin and sodium amid, the former preferably as salt, with or without dil- 5 uents, into retorts appropriately heated beforehand, &c.

The practical carrying out of the process may be illustrated, for instance, as follows:

Manufacture of mdomylfromphenylglycin- 4o phenyZgZyc m.In a suitable retort-like vessel is molten a mixture of forty-five kilograms of caustic potash, thirty-five kilograms of gerial No. 74,319 (No specimens.)

caustic soda, and fifteen kilograms of sodium amid or a mixture of fifteen kilograms of potassium cyanid and fifteen kilograms of sodium amid, and the melting mass is introduced at about 180 to 210 centigrade into fifteen kilograms of the potassium salt of phenylglycinphenylglycin. The ammonia escapin g hereby facilitates the necessary exclusion of air. The melt is complete as soon as the evolution of ammonia diminishes. When cold, it is poured into water and transformed in the usual manner into indoxyl or indigo.

If in the above example phenylglycinphenylglycin be substituted by one of its homologues, especially ortho-tolylglycin-ortho-tolylglycin, (Journ. f. Prakt. Chem. (2) 38.302; Beilstein III, V01. 2, p. 470,) or by para-tolylglycin-para-tolylglycin, then the known h0- mologous indoxyls or indigoes may be obtained.

Having now described our invention, what we claim is 1. The herein-described process of making indoxyl, which consists in causing sodium amid to act ata high temperature preferably with suitable diluents on phenylglycinphenylglycin (phenylglycinphenylglycid), substantially as set forth.

2. The'herein-deseribed process of making indoxyl, which consists in reacting with sodium amid at a high temperature on a homologous phenylglycinphenylglycid,substantially as set forth.

In testimony that We claim the foregoing as our invention we havesigned our names in presence of two subscribing witnesses.

' BENNO HOMOLKA.

orro LIEBKNECHT.

Witnesses ALFRED BRISBOIS, HEINRICH HAHN. 

